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Solid-state microwave amplification into millimetric frequencies

Abstract:

The work presented in this thesis is published research work undertaken by the author
over a long period of time 1975 to 2004, and to assist the reader it is split into three
periods. The first period covers 1975 to 1979 and concentrates on the research and
development of the silicon TRAPATI diode for use in an X-band power amplifier
suitable for airborne application. The work includes the development and measurement of
the thermal operation of the diode, the microwave circuit design required for the class - C
reflection amplifier operation and an in depth analysis of the technical problems
associated with the design of high-frequency TRAP A IT circuits, which final led to the
decline of the technology at frequencies beyond S-band.
The second period covers 1980 to 1987 and describes in detail the authors' contribution
in the development of a milli-metric GaAs MESFET giving state of the art minimum
noise performance in the mid 1980's. The work covers research into the design aspects of
the transistor, and in particular the RF characterization and the development of an
equivalent circuit model. The minimum noise figure measurements were compared with
Fukui model and deviation at the high frequency was identified and was attributed to
distributed effects along the electrode metallization patterns. The work also led to the
invention of a new travelling wave structure, the LGT (linear gate transistor) which was
fabricated and fully RF characterized. The work describes the LGT structure in detail
which was ahead of its time with respect to the available technology for fabrication.
The third period covers 2000 to 2004 where the author extended his research work into
microwave transistors fabricated on wide band-gap materials, for example Gallium
Nitride (GaN). The work includes noise analysis of the GaN high electron mobility
transistor (HEMT) using the Fukui analysis. The prime part of the work has been in
'extracting the intrinsic device parameters over bias conditions, which has led to novel
method of extracting the parasitic source resistance (R.) and the intrinsic saturation
velocity (V.i). The extracted intrinsic parameters are used for both large signal and
minimum noise analysis.